Biology subjects

Janda, M.

Publications and source records attributed to Janda, M..

8 recordsLinked to original sources

bioRxiv2025

Salicylic acid accumulation correlates with low anthocyanin production in Arabidopsis

Anthocyanins, flavonoid pigments, are essential photoprotective agents and play a pivotal role in enhancing plant resilience to environmental stressors. It has been shown that anthocyanin production is inhibited when pattern-triggered immunity (PTI) is activated in Arabidopsis thaliana. An important component of PTI is the phytohormone salicylic acid (SA). Interestingly, exogenous treatment with SA has been shown to induce anthocyanin content in grape, apple, maize roots, rose callus, or Arabidopsis seedlings. In this study, we used several A. thaliana mutants with modulated SA content to decipher the role of endogenous SA in anthocyanin production in A. thaliana. We treated WT and mutants with anthocyanin-inducible conditions and measured anthocyanin content using spectroscopy. We showed that high endogenous SA accumulation correlates with low anthocyanin production. This was confirmed by the treatment of the A. thaliana seedlings with exogenous SA. Additionally, using microscopy in the 5gt mutant, which exhibits enhanced production of anthocyanin vesicular inclusions (AVIs) due to the inhibition of ligandin-dependent vacuolar import, we showed that high endogenous SA also correlates with lower AVI abundance. Comparative analysis of Arabidopsis WT and mutants used in this study indicates a possible inhibitory effect of SA accumulation on anthocyanin content under anthocyanin-inducible conditions (AICs). We suggest that under AICs, SA downstream signaling independent of NPR1 is responsible for lower anthocyanin accumulation. HighlightsO_LIHigh endogenous SA correlates with low anthocyanin content under AIC in Arabidopsis C_LIO_LISA signaling, not biosynthesis, is responsible for the inhibition of anthocyanins C_LIO_LIHigh SA concentration decreases the abundance of AVI bodies C_LI GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=146 HEIGHT=200 SRC="FIGDIR/small/658514v1_ufig1.gif" ALT="Figure 1"> View larger version (31K): org.highwire.dtl.DTLVardef@183500corg.highwire.dtl.DTLVardef@1fc5e3forg.highwire.dtl.DTLVardef@18fb48forg.highwire.dtl.DTLVardef@1975181_HPS_FORMAT_FIGEXP M_FIG C_FIG Graphical abstract. Anthocyanin-inducible conditions (AICs), such as changes in day length, high sucrose in the medium, or treatment with kinetin, trigger the biosynthesis of anthocyanins. Previously, it was shown that activated pattern-triggered immunity (PTI), caused by the recognition of microbe-associated molecular patterns (MAMPs) by pattern recognition receptors (PRRs), inhibits anthocyanin production. A typical PTI response is an increased production of salicylic acid (SA). In this study, we show that a high concentration of SA and its downstream signaling, rather than SA biosynthesis itself, reduces anthocyanin accumulation.

plant biology↗

bioRxiv2025

Pattern-triggered immunity in blue and white seed cultivars of Papaver somniferum

Papaver somniferum (poppy) is a traditional component of Central and Eastern European cuisine and an important oilseed crop in the region. The crucial thread for poppy stable yield is pathogen infection. Thus, we need to understand poppy defence mechanisms in detail. The first robust layer of plant immunity, which plays a crucial role in combat against pathogens, is pattern-triggered immunity (PTI). Here, we provide the first insights into PTI in poppy. We selected four poppy varieties used in the food industry. We investigated poppy response to various peptide elicitors acting as microbe-associated molecular patterns (MAMPs) and damage-associated molecular patterns (DAMPs). Flg22 induced the most robust reactive oxygen species (ROS) burst among all tested peptides. Flg22 also triggered putative mitogen-activated protein kinase (MAPK) phosphorylation and seedling growth inhibition in all tested cultivars. We identified PsWRKY22 and PsPR2 as candidate marker genes suitable for monitoring poppy PTI responses. The tested poppy cultivars have low levels of salicylic acid. Callose accumulation was triggered by wounding but not by flg22. For studying PTI in poppy, wounding is a challenge that needs to be considered as it can obscure potential PTI responses. Our findings highlight conserved aspects of poppy immunity and challenges in studying poppy PTI. The established pipeline facilitates improving our understanding of poppy immunity and has the potential for widespread application in poppy breeding and improving selection for broad-spectrum disease resistance provided by enhanced PTI. GRAPHICAL ABSTRACT O_FIG O_LINKSMALLFIG WIDTH=200 HEIGHT=147 SRC="FIGDIR/small/639761v1_ufig1.gif" ALT="Figure 1"> View larger version (39K): org.highwire.dtl.DTLVardef@1680d52org.highwire.dtl.DTLVardef@42895eorg.highwire.dtl.DTLVardef@488ffeorg.highwire.dtl.DTLVardef@1e5a95d_HPS_FORMAT_FIGEXP M_FIG Graphical abstract The establishment of the methods for studying pattern-triggered immunity (PTI) in Papaver somniferum L. (poppy) was inspired by the knowledge of the model plant Arabidopsis thaliana. The study showed a similarity between Arabidopsis and poppy in response to flg22 but also pointed out the obstacles for PTI analysis in poppy and the differences compared to the model plant. Created with BioRender.com. C_FIG

plant biology↗

bioRxiv2025

Armadillo Repeat Only Proteins Are Crucial for the Function of Plant CNGC Channels

The versatile Ca2+ signaling system governs plant responses to a wide array of environmental and developmental cues. CYCLIC NUCLEOTIDE-GATED CHANNELS (CNGCs) trigger cellular responses to diverse signals, including phytohormones, biotic and abiotic stresses; and as such their activity is tightly controlled. Unlike their animal paralogs, plant CNGCs does not seem to be gated by cyclic nucleotides, and the mechanism of their activation remains unresolved. Here we report ARMADILLO REPEAT ONLY (ARO) proteins as novel, plant-specific, and essential activators of plant CNGCs. Reciprocal proximity labeling revealed interactions between all sporophytic CNGCs and AROs. Loss-of-function aro mutants fail to induce Ca2+ transients in response to known CNGC-triggering stimuli. Structural modeling, mutational analysis, and electrophysiological data show that AROs assemble into a complex with CNGC tetramers by interaction with the conserved Calmodulin-binding IQ domain. AROs represent CNGC activators, competing with Calmodulins, showcasing an evolutionarily unique solution to regulation of calcium signaling in plants.

plant biology↗

bioRxiv2021

Biophysical and proteomic analyses suggest functions of Pseudomonas syringae pv tomato DC3000 extracellular vesicles in bacterial growth during plant infection

Vesiculation is a process employed by Gram-negative bacteria to release extracellular vesicles (EVs) into the environment. Bacterial EVs contain molecular cargo from the donor bacterium and play important roles in bacterial survival and growth. Here, we describe EV production in plant-pathogenic Pseudomonas syringae pv. tomato DC3000 (Pto DC3000), the causal agent of bacterial speck disease. Cultured Pto DC3000 exhibited EV structures both on the cell surface and in the vicinity of bacterial cells, observed as outer membrane vesicle (OMV) release. We used in-solution trypsin digestion coupled to mass spectrometry to identify 369 proteins enriched in EVs recovered from cultured Pto DC3000. The predicted localization profile of EV proteins supports the production of EVs also in the form of outer-inner-membrane vesicles (OIMVs). EV production varied slightly between bacterial lifestyles and also occurred in planta. The potential contribution of EVs to Pto DC3000 plant infection was assessed using plant treatments and bioinformatic analysis of the EV-enriched proteins. While these results identify immunogenic activities of the EVs, they also point at roles for EVs in bacterial defences and nutrient acquisition by Pto DC3000.

plant biology↗

bioRxiv2019

Influence Of Salt Stress On The flg22 Induced ROS Production In Arabidopsis thaliana Leaves

In their natural habitats, plants have to cope with multiple stress factors triggering respective response pathways, leading to mutual interference. Our work aimed to study the effect of salt stress in combination with immune response triggered by microbe-associated molecular pattern (MAMP) in Arabidopsis thaliana Col-0 plants. We measured ROS production after treatment with flg22 and the influence of concomitant salt stress (NaCl and Na2CO3).The maximum combined effect of NaCl solution and flg22 on ROS production was achieved at 6 mM salt, which was almost 2 times higher than the single effect of MAMP. A similar maximum combined effect with Na2CO3 was observed at 10 mM concentration. High concentration of NaCl and Na2CO3 was accompanied with declining of ROS production, which was completely inhibited at 150 mM of NaCl and at 50 mM of Na2CO3.The immediate and long term (24 h) effect of NaCl on leaf tissue of Arabidopsis thaliana showed that the impact of salt stress on flg22induced ROS production probably did not affect the genetic aspects of the tissue response, but was associated with ionic and osmotic stresses. Experiments with mannitol, KCl and CaCl2 allowed to conclude that the observed effect was due to the ionic stress of the salt rather than the osmotic one.

physiology↗

bioRxiv2019

Spatial metabolomics of in situ, host-microbe interactions

Spatial metabolomics describes the location and chemistry of small molecules involved in metabolic phenotypes, defense molecules and chemical interactions in natural communities. Most current techniques are unable to spatially link the genotype and metabolic phenotype of microorganisms in situ at a scale relevant to microbial interactions. Here, we present a spatial metabolomics pipeline (metaFISH) that combines fluorescence in situ hybridization (FISH) microscopy and high-resolution atmospheric pressure mass spectrometry imaging (AP-MALDI-MSI) to image host-microbe symbioses and their metabolic interactions. metaFISH aligns and integrates metabolite and fluorescent images at the micrometer-scale for a spatial assignment of host and symbiont metabolites on the same tissue section. To illustrate the advantages of metaFISH, we mapped the spatial metabolome of a deep-sea mussel and its intracellular symbiotic bacteria at the scale of individual epithelial host cells. Our analytical pipeline revealed metabolic adaptations of the epithelial cells to the intracellular symbionts, a variation in metabolic phenotypes in one symbiont type, and novel symbiosis metabolites. metaFISH provides a culture-independent approach to link metabolic phenotypes to community members in situ - a powerful tool for microbiologists across fields.

microbiology↗

bioRxiv2018

Evolution of the latitudinal diversity gradient in the hyperdiverse ant genus Pheidole

AimThe latitudinal diversity gradient is the dominant pattern of life on Earth, but a consensus understanding of its origins has remained elusive. The analysis of recently diverged, hyper-rich invertebrate groups provides an opportunity to investigate latitudinal patterns with the statistical power of large trees while minimizing potentially confounding variation in ecology and history. Here, we synthesize global phylogenetic and macroecological data on a hyperdiverse (>1100 species) ant radiation, Pheidole, and evaluate the roles of three general explanations for the latitudinal gradient: variation in diversification rate, tropical conservatism, and ecological regulation.\n\nLocationGlobal.\n\nTime PeriodThe past 35 million years.\n\nMajor taxa studiedThe hyperdiverse ant genus Pheidole Westwood.\n\nMethodsWe assembled geographic data for 1499 species and morphospecies, and inferred a dated phylogeny of Pheidole of 449 species, including 150 species newly sequenced for this study. We tested correlations between diversification rate and latitude with BAMM, HiSSE, GeoSSE, and FiSSE, and examined patterns of diversification as Pheidole spread around the globe.\n\nResultsWe found that Pheidole diversification occurred in series of bursts when new continents were colonized, followed by a slowdown in each region. There was no evidence of systematic variation of net diversification rates with latitude across any of the methods. Additionally, we found latitudinal affinity is moderately conserved with a Neotropical ancestor and phylogenetic inertia alone is sufficient to produce the gradient pattern.\n\nMain ConclusionsOverall our results are consistent with tropical conservatism explaining the diversity gradient, while providing no evidence that diversification rate varies systematically with latitude. There is evidence of ecological regulation on continental scales through the pattern of diversification after colonization. These results shed light on the mechanisms underlying the diversity gradient, while contributing toward a much-needed invertebrate perspective on global biodiversity dynamics.

evolutionary biology↗

bioRxiv2018

Can Actin Depolymerization Actually Result In Increased Plant Resistance To Pathogens?

Introductory paragraphThe integrity of the actin cytoskeleton is essential for plant immune signalling1. Consequently, it is generally assumed that actin disruption reduces plant resistance to pathogen attack2-4. However, in a previous study, it was shown that actin depolymerisation triggers the salicylic acid (SA) signalling pathway5, which is interesting because increased SA is associated with enhanced plant resistance to pathogen attack6,7. Here, we attempt to resolve this seeming inconsistency by showing that the relationship between actin depolymerization and plant resistance is more complex than currently thought. We investigate the precise nature of this relationship using two completely different plant pathosystems: i) a model plant (Arabidopsis thaliana) and a bacterial pathogen (Pseudomonas syringae), and ii) an important crop (Brassica napus) and a fungal pathogen (Leptosphaeria maculans). We demonstrate that actin depolymerization induces a dramatic increase in SA levels and that the increased SA is biosynthesized by the isochorismate synthase pathway. In both pathosystems, this phenomenon leads to increased plant resistance.

plant biology↗